Combustion turbine cooling media supply system and related method

ABSTRACT

A land based gas turbine apparatus includes an integral compressor; a turbine component having a combustor to which air from the integral compressor and fuel are supplied; and a generator operatively connected to the turbine for generating electricity; wherein hot gas path component parts in the turbine component are cooled entirely or at least partially by cooling air or other cooling media supplied by an external compressor. A method is also provided which includes the steps of supplying compressed air to the combustor from the integral compressor; and supplying at least a portion of the cooling air or other cooling media to the hot gas path parts in the turbine component from an external compressor.

This invention relates to supplying augmenting compressed air and/or cooling media to a combustion turbine via a separate compressor. For the case of cooling media supply, the media may be conditioned, e.g., cooled and/or humidified.

BACKGROUND OF THE INVENTION

Most combustion turbines use air bled from one or more locations of the integral compressor to provide for cooling and sealing in the turbine component. Air bled from the compressor for this purpose may be routed internally through the bore of the compressor-turbine rotor or other suitable internal passages to the locations that require cooling and sealing in the turbine section. Alternatively, air may be routed externally through the compressor casing and through external (to the casing) piping to the locations that require cooling and sealing. Many combustion turbines utilize a combination of the internal and external routing of cooling and sealing air to the turbine component. Some combustion turbines use heat exchangers to cool the cooling and sealing air routed through the external piping before introduction into the turbine component.

The output or capacity of a combustion turbine usually falls off with increasing temperature at the inlet to the compressor component. Specifically, the capacity of the compressor component to supply air to the combustion process and subsequent expansion through the turbine is reduced as the compressor inlet temperature is increased (usually due to increased ambient temperature). Thus, the turbine component and combustion component of the combustion turbine usually have the capability to accept more compressed air than the compressor component can supply when operating above a certain inlet temperature.

SUMMARY OF THE INVENTION

In accordance with one embodiment of this invention, the supply of pressurized air to the combustion and turbine components is augmented by use of an external compressor when the capability of the integral compressor is reduced, thereby increasing the output of the combustion turbine or combined cycle power plant.

There are, however, several ways to utilize the external compressor. One way is to insert compressed ambient air into the combustion turbine flow path at the exit of the compressor component and/or in the combustion component before fuel addition. (This will be referred to as “pure augmentation” air supply).

Another way of using the external compressor is to incorporate it into a system for supplying conditioned cooling and sealing media to the turbine component. This may be done combined with the pure augmentation method described above, or separately in the event the pure augmentation method is not utilized. The supply of cooling media by the external supply system reduces that which would normally be supplied through extraction from the integral compressor component of the combustion turbine, allowing more air from the integral compressor to be directed to the combustion component, thereby increasing output.

In its broader aspects, therefore, the invention relates to a land based gas turbine apparatus comprising an integral compressor; a turbine component having a combustor to which air from the integral compressor and fuel are supplied; and a generator operatively connected to the turbine for generating electricity; wherein hot component parts in the turbine component are cooled at least partially by air or other cooling media supplied by an external compressor.

In another aspect, the invention relates to a method of insuring peak power capability for a gas turbine power plant including an integral compressor, a turbine component including a combustor and a generator, wherein hot gas path parts in the turbine component are cooled by cooling air, the method comprising supplying compressed air to said combustor from the internal compressor; and supplying at least a portion of the cooling air or other cooling media to the hot gas path parts in the turbine component from an external compressor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a known cooling arrangement for a combustion turbine;

FIG. 2 is a schematic diagram of a cooling arrangement for a combustion turbine in accordance with an exemplary embodiment of this invention;

FIG. 3 is a schematic diagram of a cooling arrangement for a combustion turbine in accordance with another exemplary embodiment of the invention; and

FIG. 4 is a schematic diagram of a cooling arrangement for a combustion turbine in accordance with still another embodiment of the invention.

DESCRIPTION OF THE INVENTION

FIG. 1 represents a conventional cooled combustion turbine system including an integral compressor 10, combustor 12 and turbine component 14. Inlet air is supplied to the compressor via stream 16. Compressor air is extracted from various locations in the compressor and supplied to the locations in the turbine component 14 that require cooling and sealing. Remaining compressor air is supplied to the combustor. The extraction locations are chosen to supply air at the required pressures. This remaining air is compressed air is supplied at high pressure to the combustor via stream 18 where it mixes with fuel supplied by stream 20. The hot combustion gas is supplied to the turbine component 14 via stream 22. Some compressor air may be diverted to bypass the combustor via stream 24, entering the hot combustion gases before entering the turbine. The flow streams 26, 28 and 30 represent cooling air extractions from the integral compressor that are routed to the, turbine section of the machine for cooling and sealing hot gas path component parts. Streams 26 and 28 that supply the low and intermediate pressure coolant, respectively, may be routed via piping external to the compressor casing, and reintroduced through the turbine casing into the parts that need cooling. Stream 30 supplies the high pressure coolant and is typically routed internally of the machine, for example, through the bore of the compressor-turbine rotor. The compressor 10, turbine section 14 and generator 32 are shown in a single shaft configuration with the single shaft 34 also driving the generator 32.

FIG. 2 illustrates an example of the present invention and where, for the sake of convenience and ease of understanding, reference numerals similar to those used in FIG. 1 are applied to corresponding components, but with the prefix “1” added. As in the conventional system described above, inlet air is supplied to the compressor 110 via stream 116. Compressed air is supplied to the combustor 112 via stream 118 where it mixes with fuel supplied to the combustor via stream 120. Bypass air may be supplied to the hot combustion gases via stream 124. Here, however, the respective low, intermediate and high pressure cooling air streams 126,128 and 130 (or other cooling media) are generated by a separate external compressor 136 driven by a motor 138. In this embodiment, all of the air or other cooling media is supplied by the external compressor 136, thus allowing more of the combustion turbine compressor air to be used in the combustion process. Because the compressor 136 can be dedicated for supplying only cooling air or other cooling media, the cooling requirements of the turbine component can be met regardless of compressor capability variations due to increased ambient temperatures. In other words, because the integral compressor 110 is freed from cooling duty requirements, sufficient air is available to satisfy the capability of the combustor and turbine component, thereby increasing output.

FIG. 3 illustrates a variation where cooling air is supplied by both the integral turbine compressor 210 and by the external compressor 236 (this could be an intercooled compressor) in a pure augmentation technique. In other words, the external compressor 236 is utilized to augment the supply of compressed air from the integral compressor 210 to the turbine component for cooling and sealing purposes. Here, the low, intermediate and high pressure cooling air is supplied by integral compressor 210 via respective streams 226, 228 and 230, but supplemented as necessary by cooling air supplied by external compressor 236 via respective low, intermediate and high pressure streams 242, 244 and 246. Because the cooling duty requirements are augmented by the external compressor 236, the supply of compressed air to the combustor 212 from the compressor 210 is increased resulting in increased output.

Optionally, as shown in FIG. 4, compressed air from stream 246 can be supplied to the combustor via line 218 (rather than to the turbine section via stream 230) to augment the supply of air from the integral compressor 210. Otherwise, the arrangement in FIG. 4 is identical to the arrangement in FIG. 3. Moreover, the augmented supply of cooling media to the turbine section 214 via streams 242 and 244 can be shut off, so that the external compressor augments the air supply only to the combustor.

Additional features can be added to the separate air cooling media supply system, such as humidification of the cooling media. One suitable means of humidification employs a saturator and hot water heated by waste or primary energy. Moisture introduction is shown in FIGS. 2 and 3 via streams 140, and 240, respectively. Waste heat is readily available from the turbine exhaust in single cycle systems for evaporation of water that can then be introduced into any of the discharge air streams of compressor 136 or 236, as appropriate. The coolant supply system can modulate the flow, pressure, temperature and composition of the supplied cooling media.

The above described invention thus provides peak power capability for a gas turbine, particularly when ambient temperature rises to a level that causes reduced flow to the integral turbine compressor, resulting in reduced output. In other words, as ambient temperature rises and air flow into the turbine compressor decreases, the external compressor 136 or 236 may be employed to maintain or increase output by supplying all, or additional cooling air (or other cooling media) in an amount necessary to optimize the flow of cooling air to the hot gas path parts of the turbine sections and/or to augment the flow of air or other cooling media to the combustion process. Further in this regard, by using an external compressor, greater cooling air flow can be provided than that available from the integral turbine compressor since only a small percentage of air from the turbine compressor is available for cooling duty. In other words, in conventional systems the amount of cooling air is limited by the capacity of the integral compressor. By supplying cooling air from an external compressor where all of the air or other cooling media may be used for cooling duty, the turbine compressor can supply more air to the combustion process, thereby increasing turbine output. This is true whether the external compressor 136, 236 is used alone or in conjunction with the integral turbine compressor 110, 210.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 

What is claimed is:
 1. A land based combustion gas turbine apparatus comprising: an integral compressor; a turbine component; a combustor to which air from the integral compressor and fuel are supplied, said combustor arranged to supply hot combustion gases to the turbine component; a generator operatively connected to the turbine for generating electricity; and an external compressor arranged and connected to supply cooling air or other cooling media, without intercooling, to hot gas path component parts in said turbine component.
 2. The apparatus of claim 1 including means for humidifying said cooling air or other cooling media.
 3. The apparatus of claim 1 wherein all of said cooling air or other cooling media is supplied by said external compressor.
 4. A method of insuring peak power capability for a land based gas turbine power plant including an integral compressor, a turbine component, a combustor and a generator, wherein hot gas path parts in the turbine component are cooled by cooling air, the method comprising: a) supplying compressed air to said combustor from said integral compressor; and b) supplying cooling air or other cooling media to said hot gas path parts in the turbine component from an external compressor, without intercooling.
 5. The method of claim 4 including humidifying said cooling air or other cooling media supplied by said external compressor.
 6. The method of claim 4 wherein step (b) is commenced as a function of ambient temperature.
 7. The method of claim 4 wherein step (b) is commenced as a function of air flow rate through the integral compressor.
 8. The method of claim 4 wherein all of the cooling air or other cooling media to said hot gas path parts is supplied by the external compressor. 